CN108444855B - Device and method for rapidly analyzing content of methane in air - Google Patents
Device and method for rapidly analyzing content of methane in air Download PDFInfo
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- CN108444855B CN108444855B CN201810639195.2A CN201810639195A CN108444855B CN 108444855 B CN108444855 B CN 108444855B CN 201810639195 A CN201810639195 A CN 201810639195A CN 108444855 B CN108444855 B CN 108444855B
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- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 title claims abstract description 122
- 238000000034 method Methods 0.000 title claims abstract description 18
- 238000004458 analytical method Methods 0.000 claims abstract description 31
- 239000010935 stainless steel Substances 0.000 claims description 13
- 229910001220 stainless steel Inorganic materials 0.000 claims description 13
- 238000005086 pumping Methods 0.000 claims description 6
- 239000003638 chemical reducing agent Substances 0.000 claims description 5
- 238000003860 storage Methods 0.000 claims description 3
- 238000004868 gas analysis Methods 0.000 claims 1
- 238000001514 detection method Methods 0.000 abstract description 13
- 238000012423 maintenance Methods 0.000 abstract description 6
- 239000000463 material Substances 0.000 abstract description 5
- 239000007789 gas Substances 0.000 description 127
- PXHVJJICTQNCMI-UHFFFAOYSA-N Nickel Chemical compound [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 description 4
- 238000004587 chromatography analysis Methods 0.000 description 4
- 238000004519 manufacturing process Methods 0.000 description 4
- 238000005259 measurement Methods 0.000 description 3
- 238000012544 monitoring process Methods 0.000 description 3
- XKRFYHLGVUSROY-UHFFFAOYSA-N Argon Chemical compound [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 description 2
- 238000007084 catalytic combustion reaction Methods 0.000 description 2
- 229910052759 nickel Inorganic materials 0.000 description 2
- 238000004611 spectroscopical analysis Methods 0.000 description 2
- 239000000126 substance Substances 0.000 description 2
- 239000010963 304 stainless steel Substances 0.000 description 1
- 239000010964 304L stainless steel Substances 0.000 description 1
- 230000002159 abnormal effect Effects 0.000 description 1
- 229910052786 argon Inorganic materials 0.000 description 1
- 230000005540 biological transmission Effects 0.000 description 1
- -1 chemical engineering Substances 0.000 description 1
- 238000003889 chemical engineering Methods 0.000 description 1
- 239000003245 coal Substances 0.000 description 1
- 238000004891 communication Methods 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000010894 electron beam technology Methods 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 230000007613 environmental effect Effects 0.000 description 1
- 238000010438 heat treatment Methods 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 238000005192 partition Methods 0.000 description 1
- 239000003208 petroleum Substances 0.000 description 1
- 238000005498 polishing Methods 0.000 description 1
- 238000004321 preservation Methods 0.000 description 1
- 230000002035 prolonged effect Effects 0.000 description 1
- 238000005070 sampling Methods 0.000 description 1
- 238000007789 sealing Methods 0.000 description 1
- 239000003566 sealing material Substances 0.000 description 1
- 230000003595 spectral effect Effects 0.000 description 1
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- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N5/00—Analysing materials by weighing, e.g. weighing small particles separated from a gas or liquid
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Abstract
The invention discloses a device and a method for quickly analyzing the content of methane in air, wherein the device comprises a standard gas tank, a first container and a second container, the input end of the first container is connected with a first gas inlet branch and a second gas inlet branch, the first gas inlet branch is connected with a first valve, the second gas inlet branch is connected with the standard gas tank through a second valve, and the first gas inlet branch and the second gas inlet branch are connected in parallel and are converged to form a gas inlet; the input end of the first container is also connected with a heat exchanger, and the heat exchanger is communicated with the air inlet; the output end of the first container is connected with the input end of the second container through an output branch, and the output branch comprises a first output branch and/or a second output branch; the air inlet, the first container and the second container are all connected with a vacuum pump. The invention can realize the rapid and accurate analysis of the methane content in the air, and has wide detection range; the whole can realize automation, and the method is simple and convenient; the cost is low, no material consumption is needed, the structure is compact, and the maintenance is free.
Description
Technical Field
The invention relates to the technical field of industrial safety monitoring, in particular to a device and a method for quickly analyzing methane content in air.
Background
Methane gas is one of the main factors seriously threatening the safety production of industries such as petroleum, chemical engineering, coal and the like, safety accidents caused by the methane gas are still frequently generated in recent years, the safety production situation is still very severe, and the rapid, accurate and continuous monitoring of the methane content in the air is an important guarantee for the safety production of the modern industry.
At present, methane detection applied in industrial processes mainly comprises methane determination alarms, power-off instruments, sensors, spectroscopy and chromatography based on various catalytic combustion principles. Although these methods are improved with the development of the instrument science, there are still many bottlenecks to be solved.
Firstly, although the chromatography and the spectroscopy can measure the methane content in a wide range, the analysis efficiency is low, the method is complex, complicated analysis and calibration work needs to be carried out by professionals before measurement, equipment maintenance is difficult, and the requirement of a process field on rapid and continuous detection of the methane content is difficult to meet. Secondly, although methane detectors, sensors and the like based on the catalytic combustion principle can quickly correspond to methane in air, the measurement range is narrow, only methane in ppm level to several percent level can be detected, the measurement precision is low, the accuracy and the environmental adaptability are poor, the analysis and detection tasks under complicated and severe working conditions are difficult to undertake, and accurate response to methane data and sources in abnormal events cannot be made. Thirdly, no matter the methane alarm, the sensor and the detector or various chromatographic and spectral methane detection methods, national standard substances are adopted to calibrate instrument drift, reading error, background interference and the like, the quantity of the detectors, the alarm, the sampler and the like distributed on a process field is large, the instruments are frequently used, more standard substances are required to be used, more manpower and material resources are input, the cost is high, and the economic applicability is poor.
Therefore, it is an urgent need to solve the above-mentioned problems in the prior art by providing a device and a method for rapidly analyzing the methane content in air.
Disclosure of Invention
The invention aims to provide a device and a method for quickly analyzing the content of methane in air, which have the advantages of simple method, quick and accurate analysis, wide detection range, low cost and strong adaptability and are used for solving the problems of low analysis accuracy, narrow detection range, inconvenient maintenance and the like of the existing method for analyzing the content of methane in air.
In order to achieve the purpose, the invention provides the following scheme: the invention provides a device for quickly analyzing the content of methane in air, which comprises a standard gas tank, a first container and a second container, wherein the input end of the first container is connected with a first gas inlet branch and a second gas inlet branch, the first gas inlet branch is connected with a first valve and used for injecting gas to be analyzed, the second gas inlet branch is connected with the standard gas tank through a second valve and used for injecting standard gas, and the first gas inlet branch and the second gas inlet branch are connected in parallel and converged to form a gas inlet;
the input end of the first container is also connected with a heat exchanger, and the heat exchanger is communicated with the air inlet; the output end of the first container is connected with the input end of the second container through an output branch, and the output branch comprises a first output branch and/or a second output branch; the first output branch is sequentially connected with a fifth automatic valve and a first mass flowmeter in series, the second output branch is sequentially connected with a third valve, a volume control device and a second mass flowmeter in series, and the first output branch and the second output branch are arranged in parallel;
the air inlet, the first container and the second container are all connected with a vacuum pump through vacuum valves.
Preferably, the air inlet is connected with the input end of the heat exchanger through three air paths, the three air paths are arranged in parallel, and the output end of the air inlet is connected with a first pressure sensor.
Preferably, the three routes the gas circuit includes first gas circuit, second gas circuit and third gas circuit, first gas circuit establishes ties first automatic valve, booster pump and second automatic valve in proper order, be provided with the third automatic valve on the second gas circuit, the third gas circuit establishes ties pressure reducer and fourth automatic valve in proper order.
Preferably, the first container is further connected with a second pressure sensor and a temperature sensor, and the second container is further connected with a vacuum gauge through a first vacuum valve.
Preferably, when the first output branch is arranged between the output end of the first container and the input end of the second container, the first container and the second container are arranged in a thermostatic device, and the output branch, the second pressure sensor, the temperature sensor, the first vacuum valve and the vacuum gauge are all arranged in the thermostatic device.
Preferably, the output end of the gas inlet is connected with a second vacuum valve, the output end of the first container is connected with a third vacuum valve, the vacuum pump is connected with the second vacuum valve and the third vacuum valve through a fourth vacuum valve, and the output end of the second container is connected with the vacuum pump through a fifth vacuum valve; the second vacuum valve, the third vacuum valve and the fifth vacuum valve are arranged in parallel.
Preferably, the standard gas tank is a stainless steel gas storage tank with the pressure resistance of not less than 10MPa, and the standard gas in the standard gas tank is a preset methane-air mixed gas with known methane content; the first container is a stainless steel tank which is 5 mL-10L in volume, calibrated in volume and resistant to pressure of not less than 10 MPa; the second container is a stainless steel tank with a volume not less than 5 times of the volume of the first container and a pressure resistance not less than 2 MPa.
Preferably, the volume control device is a thermal gas volume flow controller having a volume error of no more than 0.5% and a pressure ranging from 0.1psi to 1000 psi.
Preferably, the vacuum pump is a dry pump with ultimate vacuum superior to 5Pa, and the pumping speed is not less than 5L/s.
The invention also discloses an air methane content analysis method based on the quick analysis device for the air methane content, which comprises the following steps:
step 1) making a standard curve: firstly, evacuating a pipeline of an analysis device by using a vacuum pump until the vacuum degree is superior to 5 Pa; secondly, respectively connecting the methane-air mixed gas with known methane content in the standard gas tank with the input end of a second valve in sequence, injecting the mixed gas into an analysis device, and automatically controlling the standard gas to enter a first container from a first gas path, a second gas path or a third gas path according to the pressure value fed back by a first pressure sensor; the step of vacuumizing the pipeline is repeated every time the first container is fed with the methane-air mixed gas with known methane content;
if the gas at the output end of the first container enters the second container through the first output branch, the gas output is controlled through the cooperation of the first pressure sensor and the fifth automatic valve, the pressure and the temperature of the known gas entering the first container at each time are adjusted to be consistent, the pressure is not less than 0.5MPa, then the gas in the first container is controlled to enter the second container, the gas quality is measured through the first mass flow meter, and the pressure drop of the gas in the first container at each time is ensured to be consistent; if the gas at the output end of the first container enters the second container through the second output branch and the output gas of the first container is controlled by the volume control device, the mass of the gas is measured by adopting a second mass flowmeter, and the volume of the gas entering the second container is controlled by the volume control device to be consistent under a standard state; taking the mass of the gas as an x axis, taking the content of methane as a y axis, and making a standard curve;
step 2) analysis of sample gas: after the vacuum degree of the pipeline is evacuated to be more than 5Pa by using a vacuum pump, gas to be analyzed is input from a first valve, and the system automatically controls the gas to enter a first container from a first gas circuit, a second gas circuit or a third gas circuit according to the pressure indicated by a first pressure sensor;
if the gas at the output end of the first container enters the second container through the first output branch, controlling the gas output through the cooperation of the first pressure sensor and the fifth automatic valve, adjusting the temperature and pressure conditions of the first container to ensure that the temperature and pressure conditions of the first container are consistent with those of the standard curve manufactured in the step 1), then controlling the gas to enter the second container, metering the gas quality by adopting a first mass flowmeter, and ensuring that the pressure drop of the first container is the same as that of the known gas; if the gas at the output end of the first container enters the second container through the second output branch, controlling the output gas of the first container through the volume control device, and controlling the volume of the gas entering the second container to be consistent with that of the gas entering the second container in the standard state when the standard curve is manufactured in the step 1), and metering the mass of the gas by adopting a second mass flowmeter;
and substituting the gas quality into the standard curve to obtain the methane content of the gas to be analyzed.
Compared with the prior art, the invention has the following technical effects:
(1) the analysis and detection accuracy of the methane content in the air can be greatly improved, and the detection range is wide;
(2) the system can realize automation, is simple to operate, strong in universality and low in cost, does not need material consumption and is free from maintenance;
(3) the online or sampling detection of the methane content in the air can be realized, and the analysis result is quick and reliable.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings needed in the embodiments will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings without creative efforts.
FIG. 1 is a schematic structural diagram of a rapid analysis device for methane content in air according to the present invention;
FIG. 2 is a standard graph of the methane content of air according to the present invention;
the system comprises a pressure sensor 1, a first pressure sensor 2, a first valve 3, a second valve, a standard gas tank 4, a first automatic valve 5, a booster pump 6, a second automatic valve 7, a third automatic valve 8, a pressure reducer 9, a fourth automatic valve 10, a heat exchanger 11, a heat exchanger 12, a first container 13, a second pressure sensor 14, a temperature sensor 15, a fifth automatic valve 16, a first mass flow meter 16, a third valve 17, a volume control device 18, a second mass flow meter 19, a vacuum meter 20, a first vacuum valve 21, a second container 22, a second vacuum valve 23, a third vacuum valve 24, a fourth vacuum valve 25, a vacuum pump 26, a fifth vacuum valve 27, and a thermostatic device 28.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
The invention aims to provide a device and a method for quickly analyzing the content of methane in air, which have the advantages of simplicity, quickness and accuracy in analysis, wide detection range, low cost and strong adaptability, and solve the problems of low analysis accuracy, narrow detection range, inconvenience in maintenance and the like in the prior art.
In order to make the aforementioned objects, features and advantages of the present invention comprehensible, embodiments accompanied with figures are described in further detail below.
Example one
As shown in fig. 1, the present embodiment provides a device for rapidly analyzing a methane content in air, including a standard gas tank 4, a first container 12, and a second container 22, where an input end of the first container 12 is connected to a first gas inlet branch and a second gas inlet branch, the first gas inlet branch is connected to a first valve 2 for injecting a gas to be analyzed, the second gas inlet branch is connected to the standard gas tank 4 through a second valve 3 for injecting a standard gas, and the first gas inlet branch and the second gas inlet branch are connected in parallel and converged to form a gas inlet;
the input end of the first container 12 is also connected with a heat exchanger 11, and the heat exchanger 11 is communicated with the air inlet; the output end of the first container 12 is connected with the input end of the second container 22 through an output branch, and the output branch comprises a first output branch and/or a second output branch; the first output branch is sequentially connected with a fifth automatic valve 15 and a first mass flow meter 16 in series, the second output branch is sequentially connected with a third valve 17, a volume control device 18 and a second mass flow meter 19 in series, and the first output branch and the second output branch are arranged in parallel;
the gas inlet, the first container 12 and the second container are connected to a vacuum pump 26 through vacuum valves.
The air inlet is connected with the input end of the heat exchanger 11 through three air paths which are arranged in parallel, and the output end of the air inlet is connected with the first pressure sensor 1. The three-way gas circuit comprises a first gas circuit, a second gas circuit and a third gas circuit, the first gas circuit is sequentially connected with a first automatic valve 5, a booster pump 6 and a second automatic valve 7 in series, the second gas circuit is provided with a third automatic valve 8, the third gas circuit is sequentially connected with a pressure reducer 9 and a fourth automatic valve 10 in series, and the pressure reducer 9 can adopt pressure reducing equipment such as a pressure reducing valve. The first container 12 is also connected to a second pressure sensor 13 and a temperature sensor 14, and the second container 22 is also connected to a vacuum gauge 20 through a first vacuum valve 21.
The accuracy of the first pressure sensor 1 and the accuracy of the second pressure sensor 13 are both superior to the national standard of 0.5 grade, feedback signals are output, and the pressure range is selected to be 0-1MPa or 0-10MPa according to requirements; the first automatic valve 5, the second automatic valve 7, the third automatic valve 8 and the fourth automatic valve 10 are electromagnetic switch valves or pneumatic switch valves, and the pneumatic valves are preferably selected in the embodiment, can be selectively opened according to the signals fed back by the first pressure sensor 1, and can be automatically closed according to the signals fed back by the second pressure sensor 13; when the gas pressure value shown by the first pressure sensor 1 is lower than 0.5MPa, the first automatic valve 5 and the second automatic valve 7 are opened, the gas is pressurized by a first gas path where the booster pump 6 is located and enters the first container 12, and after the required pressure is reached, the first automatic valve 5 and the second automatic valve 7 are closed according to the feedback signal of the second pressure sensor 13; when the gas pressure value shown by the first pressure sensor 1 is greater than 2.0MPa, the fourth automatic valve 10 is opened, the gas is decompressed by the gas path where the decompressor 9 is located and enters the first container 12, and after the required pressure is reached, the fourth automatic valve 10 is closed according to a feedback signal of the second pressure sensor 13. The fifth automatic valve 15 is an electromagnetic switching valve or a pneumatic switching valve, preferably a pneumatic valve, and is automatically closed according to a signal fed back from the second pressure sensor 13 after being opened.
In this embodiment, the output end of the first container 12 may be provided with only the first output branch, or only the second output branch, or both the first output branch and the second output branch are provided, and when both the first output branch and the second output branch are provided, the first output branch is connected in parallel.
When a first output branch is arranged between the output end of the first container 12 and the input end of the second container 22, the first container 12, the second container 22, the output branch therebetween, the second pressure sensor 13, the temperature sensor 14, the first vacuum valve 21 and the vacuum gauge 20 are all arranged in a constant temperature device 28, the constant temperature device 28 is a constant temperature box, the temperature control precision is better than 0.5 ℃, and the temperature deviation between the temperature of the gas passing through the heat exchanger 11 and the constant temperature box is not more than 0.5 ℃. The thermostat is internally provided with a heating wire, a partition plate and a cold air outlet, one side of the thermostat is also provided with a refrigerator and a control area, and a heat preservation layer is arranged in the shell of the thermostat and can regulate the temperature and preserve the heat. If only the second outlet branch is provided or if the gas output is controlled only by the volume control device 18, the use of an oven is not necessary.
The output end of the air inlet is connected with a second vacuum valve 23, the output end of the first container 12 is connected with a third vacuum valve 24, a vacuum pump 26 is connected with the second vacuum valve 23 and the third vacuum valve 24 through a fourth vacuum valve 25, and the output end of the second container is connected with the vacuum pump 26 through a fifth vacuum valve 27; the second vacuum valve 23, the third vacuum valve 24 and the fifth vacuum valve 27 are arranged in parallel, and the vacuum-pumping treatment of the system is realized through the matching of the vacuum pump 26 and the vacuum valves.
The first valve 2, the second valve 3, the third valve 17, the first vacuum valve 21, the second vacuum valve 23, the third vacuum valve 24, the fourth vacuum valve 25 and the fifth vacuum valve 27 are automatic valves (electromagnetic switch valves or pneumatic switch valves) or manual valves (diaphragm valves, needle valves, bellows valves and the like), the pressure resistance is not less than 10MPa, and the leakage rate is better than 1 x 10-7m3·Pa·s-1Preferably, it is better than 1X 10- 9m3·Pa·s-1. The vacuum pump 26 is a dry pump with ultimate vacuum better than 5Pa and pumping speed not less than 5L/s, and the present embodiment is preferably an oil-free scroll pump with ultimate vacuum better than 5Pa and pumping speed more than 16L/s.
The standard gas tank 4 is a stainless steel gas storage tank with pressure resistance not less than 10MPa, the standard gas in the standard gas tank 4 is a pre-configured methane-air mixed gas with known methane content, and the methane-air mixed gas is contained in the embodiment, wherein the volume content of the methane is respectively 0%, 25.60%, 50.63% and 100%. The first container 12 is a stainless steel tank with the volume of 1L, calibrated by volume and pressure resistance of not less than 10 MPa; the second container is a stainless steel tank having a volume of 10L and a pressure resistance of not less than 2 MPa.
The volume control device 18 is a thermal gas volume flow controller, or other type of controller, capable of accurately controlling the passage of the same volume of gas through a second gas mass flow meter with a volume error of no more than 0.5% and a pressure range from 0.1psi to 1000 psi.
The first mass flow meter 16 and the second mass flow meter 19 are coriolis gas mass flow meters having a precision better than ± 0.5% RD + ± 0.2% FS, with a flow range of 1sccm to 100slmN2eq (preferably 1sccm to 1000 sccmN)2eq) pressure ranging from 0.1psi to 1000psi, with various communication interfaces for flow control and data transmission.
The components of the analysis device are connected by gas pipelines, the gas pipelines for connecting the components are stainless steel pipelines with inner walls subjected to electrolytic polishing, the materials of the stainless steel pipelines are 316/316L or 304/304L stainless steel, the pressure resistance is not less than 10MPa, the sealing materials are all stainless steel or pure nickel, or the stainless steel or the pure nickel is directly welded and sealed by argon arc (or electron beam or laser), the service life is prolonged, and the sealing performance is improved.
The embodiment also discloses an air methane content analysis method based on the air methane content rapid analysis device, which comprises the following steps:
before analysis, a standard gas tank 4 is connected to a second valve 3, a sample bottle containing gas to be analyzed is directly connected to a first valve 2, and the analysis device is subjected to full-system vacuum pumping, and the method comprises the following steps: opening internal valves of the first valve 2, the second valve 3, the first automatic valve 5, the second automatic valve 7, the third automatic valve 8, the fourth automatic valve 10, the fifth automatic valve 15, the third valve 17, the second vacuum valve 23, the third vacuum valve 24, the fourth vacuum valve 25, the fifth vacuum valve 27 and the volume control device 18 to evacuate the analysis system; when the pressure of the second pressure sensor 13 is less than 0.1MPa, opening a first vacuum valve 21, monitoring the system vacuum by using a vacuum gauge 20, and when the system pressure is reduced to be less than 5Pa, closing all the valves to prepare for analysis operation; the whole system vacuumizing step is needed to be carried out every time the analysis operation is carried out.
Before analysis can be performed, the analysis system needs to be calibrated with a methane-air mixture gas with known methane content. In the example, methane-air mixed gas with methane volume contents of 0%, 25.60%, 50.63% and 100% is respectively configured, and the methane content is calibrated by an Agilent gas chromatograph; and (3) opening the second valve 3, and automatically controlling the known gas to enter the first container 12 from the first gas circuit, the second gas circuit or the third gas circuit according to the instruction of the first pressure sensor 1 by the system, wherein the gas pressure in the container is 1.0 MPa.
In the embodiment, the output gas of the first container 12 enters the second container 22 through the first output branch, the gas output is controlled through the cooperation of the first pressure sensor 1 and the fifth automatic valve 15, the pressure and the temperature of the known gas entering the first container 12 each time are adjusted to be consistent, and the pressure is not less than 0.5MPa, then the gas in the first container 12 is controlled to enter the second container 22, and the fifth automatic valve 15 is automatically closed according to a signal fed back by the second pressure sensor 13; the first mass flow meter 16 detects the mass of the mixed gas as 560.0mg, 508.1mg, 461.3mg and 363.9mg respectively.
The standard curve was plotted with gas mass as x-axis coordinate and methane content (v%) as y-axis coordinate, as shown in fig. 2.
The gas to be analyzed is prepared methane-air mixed gas with certain methane content, the mixed gas is injected through the first valve 2, the pressure condition and the operation steps are the same as the above, the mass of the mixed gas passing through the first mass flow meter 16 is 485.6mg, the methane content in the mixed gas is 37.74% calculated through a standard curve, the methane content of the mixed gas is 37.72% through Agilent gas chromatographic analysis, and the new technology is consistent with the chromatographic analysis.
The invention can realize the rapid and accurate analysis of the methane content in the air, and has wide detection range; the whole can realize automation, and the method is simple and convenient; the cost is low, no material consumption is needed, the structure is compact, and the maintenance is free.
The principle and the implementation mode of the invention are explained by applying a specific example, and the description of the embodiment is only used for helping to understand the method and the core idea of the invention; meanwhile, for a person skilled in the art, according to the idea of the present invention, the specific embodiments and the application range may be changed. In view of the above, the present disclosure should not be construed as limiting the invention.
Claims (8)
1. A quick analytical equipment of methane content in air which characterized in that: the gas analysis device comprises a standard gas tank, a first container and a second container, wherein the input end of the first container is connected with a first gas inlet branch and a second gas inlet branch, the first gas inlet branch is connected with a first valve and used for injecting gas to be analyzed, the second gas inlet branch is connected with the standard gas tank through a second valve and used for injecting standard gas, and the first gas inlet branch and the second gas inlet branch are connected in parallel and are converged to form a gas inlet;
the input end of the first container is also connected with a heat exchanger, and the heat exchanger is communicated with the air inlet; the output end of the first container is connected with the input end of the second container through an output branch, and the output branch comprises a first output branch and/or a second output branch; the first output branch is sequentially connected with a fifth automatic valve and a first mass flowmeter in series, the second output branch is sequentially connected with a third valve, a volume control device and a second mass flowmeter in series, and the first output branch and the second output branch are arranged in parallel;
the air inlet, the first container and the second container are connected with a vacuum pump through vacuum valves;
the air inlet is connected with the input end of the heat exchanger through three air paths, the three air paths are arranged in parallel, and the output end of the air inlet is connected with a first pressure sensor; the gas circuit comprises a first gas circuit, a second gas circuit and a third gas circuit, wherein the first gas circuit is sequentially connected with a first automatic valve, a booster pump and a second automatic valve in series, the second gas circuit is provided with a third automatic valve, and the third gas circuit is sequentially connected with a pressure reducer and a fourth automatic valve in series.
2. The apparatus for rapidly analyzing the content of methane in the air according to claim 1, wherein: the first container is also connected with a second pressure sensor and a temperature sensor, and the second container is also connected with a vacuum gauge through a first vacuum valve.
3. The apparatus for rapidly analyzing the content of methane in the air according to claim 2, wherein: the output end of the first container and the input end of the second container are provided with the first output branch circuit, the first container and the second container are arranged in the constant temperature device, and the output branch circuit, the second pressure sensor, the temperature sensor, the first vacuum valve and the vacuum gauge are arranged in the constant temperature device.
4. The apparatus for rapidly analyzing the content of methane in the air according to claim 3, wherein: the output end of the air inlet is connected with a second vacuum valve, the output end of the first container is connected with a third vacuum valve, the vacuum pump is connected with the second vacuum valve and the third vacuum valve through a fourth vacuum valve, and the output end of the second container is connected with the vacuum pump through a fifth vacuum valve; the second vacuum valve, the third vacuum valve and the fifth vacuum valve are arranged in parallel.
5. The device for rapidly analyzing the content of methane in the air according to claim 4, wherein: the standard gas tank is a stainless steel gas storage tank with the pressure resistance of not less than 10MPa, and the standard gas in the standard gas tank is a pre-prepared methane-air mixed gas with known methane content; the first container is a stainless steel tank which is 5 mL-10L in volume, calibrated in volume and resistant to pressure of not less than 10 MPa; the second container is a stainless steel tank with a volume not less than 5 times of the volume of the first container and a pressure resistance not less than 2 MPa.
6. The rapid analysis device for the content of methane in the air according to claim 5, characterized in that: the volume control device is a thermal gas volume flow controller with a volume error of no more than 0.5% and a pressure range from 0.1psi to 1000 psi.
7. The apparatus for rapidly analyzing the content of methane in the air according to claim 6, wherein: the vacuum pump is a dry pump with ultimate vacuum superior to 5Pa, and the pumping speed is not less than 5L/s.
8. A method for analyzing the content of methane in air by using the apparatus for rapid analysis of the content of methane in air according to claim 7, comprising the steps of:
step 1) making a standard curve: firstly, evacuating a pipeline of an analysis device by using a vacuum pump until the vacuum degree is superior to 5 Pa; secondly, respectively connecting the methane-air mixed gas with known methane content in the standard gas tank with the input end of a second valve in sequence, injecting the mixed gas into the first container, and automatically controlling the standard gas to enter the first container from the first gas path, the second gas path or the third gas path according to the pressure value fed back by the first pressure sensor; the step of vacuumizing the pipeline is repeated every time the first container is fed with the methane-air mixed gas with known methane content;
if the gas at the output end of the first container enters the second container through the first output branch, the gas output is controlled through the cooperation of the first pressure sensor and the fifth automatic valve, the pressure and the temperature of the known gas entering the first container at each time are adjusted to be consistent, the pressure is not less than 0.5MPa, then the gas in the first container is controlled to enter the second container, the gas quality is measured through the first mass flow meter, and the pressure drop of the gas in the first container at each time is ensured to be consistent; if the gas at the output end of the first container enters the second container through the second output branch and the output gas of the first container is controlled by the volume control device, the mass of the gas is measured by adopting a second mass flowmeter, and the volume of the gas entering the second container is controlled by the volume control device to be consistent under a standard state; taking the mass of the gas as an x axis, taking the content of methane as a y axis, and making a standard curve;
step 2) analysis of sample gas: after the vacuum degree of the pipeline is evacuated to be more than 5Pa by using a vacuum pump, gas to be analyzed is input from a first valve, and the system automatically controls the gas to enter a first container from a first gas circuit, a second gas circuit or a third gas circuit according to the pressure indicated by a first pressure sensor;
if the gas at the output end of the first container enters the second container through the first output branch, controlling the gas output through the cooperation of the first pressure sensor and the fifth automatic valve, adjusting the temperature and pressure conditions of the first container to ensure that the temperature and pressure conditions of the first container are consistent with those of the standard curve manufactured in the step 1), then controlling the gas to enter the second container, metering the gas quality by adopting a first mass flowmeter, and ensuring that the pressure drop of the first container is the same as that of the known gas; if the gas at the output end of the first container enters the second container through the second output branch, controlling the output gas of the first container through the volume control device, and controlling the volume of the gas entering the second container to be consistent with that of the gas entering the second container in the standard state when the standard curve is manufactured in the step 1), and metering the mass of the gas by adopting a second mass flowmeter;
and substituting the gas quality into the standard curve to obtain the methane content of the gas to be analyzed.
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| CN204346877U (en) * | 2014-12-22 | 2015-05-20 | 南京五和试验设备有限公司 | A kind of mixed gas experimental system |
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| CN204346877U (en) * | 2014-12-22 | 2015-05-20 | 南京五和试验设备有限公司 | A kind of mixed gas experimental system |
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